Sound-reproducing apparatus



Oct. 22, 1929, w. BROWER 1,732,495

SOUND REPRODUCING APPARATUS Filed May 27, 1926 2 Sheets-Sheet l [/VVENTOR. r 0 W a WM?! Mam, fimow m BY 0 d K ATTORNEY Oct. 22, 1929:. w. BROWER SOUND REPRODUCING APPARATUS Filed May 27, 1926 2 Sheets-Sheet 2 LHWMM Z? Y W ldatented tilctt fillit application filed lttfay at,

My invention relates broadly to loud speaker sound reproducers and more particularly to an electromagnetic sound reproducer con-- nected in the output circuit oi electron tube amplification systems with special provision. for eliminating microphonic ieedbaclt.

One of the objects ot my invention is to provide a construction oi loud speaker elec tromagnetic sound reproducer particularly adapted :tor mounting within a cabinet which houses the electron tube amplifying apparatus and other auxiliary equipment for the loud speaker being so mounted in the cabinet that noises in the sound reproducer arising from the tendency of microphonic feedback". in the electrical circuit are substantially elim inated Another object of my invention is to provide a construction oi electromagnetic sound. reproducer suspended within a cabinet structure by sound proof material for isolating the electromagnetic sound reproducer from the effects of, microphonic feedback noises which generally arise in the circuits associated with the electromagnetic sound. reproducen A. further object of my invention is to pro-- vide a mounting for an electromagnetic sound reproducer which substantially encloses the electromagnetic sound reproducer within a removable cabinet structure in such. manner that the cabinet structure may be detachably suspended t'rom a main cabinet which houses the electron tube amplification apparatus and associated circuits but arranged in such. mam ner that noises arising from inicrophonic feedback" are substantially eliminated in the sound reproducing system Still another object ot' my invention is to provide a simplified mounting tor an electromagnetic sound reproducing system which may be readily manufactured on a quantity production basis and assembledwithin cal inet structure which houses amplification and electrical apparatus for controlling the opera tion of the clectro-magnetic sound reproducer without inter- "erenc e ifrom noises arising from microphonic feedback between the electrical circuits the electromagnetic sound. reproducing SF'SlZBlIL My invention. will be more tally understood teas. serial No. iiaea't.

from the specification hereinafter following by reference to the accompanying drawings in which:

lcigure 1 is a rear view of the electromag netic sound reproducer showing the cabinet suspended from the main cabinet structure; lg 52 is a .tront view of the main cabinet structure showing the electromagnetic sound reproducing apparatus arranged therein; l? 3 is a horizontal cross'sectional view taken alongline 33 of Fig. 2 and showing the arrangement of the sound reproducing diaphragm and the electromagnetic sound reproducer arranged within the cabinet housing and shown in position with respect to the main cabinet; Fig. 4t is a cross-sectional view showing the electromagnetic sound reproducer in position within the cabinet struc ture; and Fig. 5 shows the manner in which the sound reproducer is readily removed from or inserted into the suspension means which are provided in the cabinet structure,

lily invention contemplates the mounting of an electromagnetic sound reproducer or loud speaker in the cabinet which houses the electron tube amplification system and tun-- ing system circuits oi": a broadcast radio re ceiver. However, it desire that it be under stood that the same arrangement which-ll have shown herein may be employed. in an electrical phonograph or in any public ad dress system, or in any other arrangement where an electromagnetic sound reproducer operates in the output circuits of a sensitive electron tube amplification system There is a normal tendency for the reproduction oi nicrophonic noises in the sound re tiroducing system due to microphonic teed baclr between the sensitive electron tube am-- plilier circuits and the electroi'nagnetic sound reproducer. By my invention ll substantially eliminate the undesirable noises which occur in the sound reproducing apparatus. l: provide a housing for the electromagnetic sound reproducing apparatus and suspend this housing within. the main cabinet structure by means oft sound proof material which clamps the transfer and reproduction oi microphonic noises in the sound reproducing system.

liteterring to the drawings in. more detail "iii reference character 1 designates the main cabinet structure which contains the radio receiving apparatus or amplifying equipment. The cabinet is provided with an aperture 2 adjacent the top thereof into which the panel 3 fits, having ornamental grill work a formed therein. The electromagnetic sound reproducing apparatus is contained within a housing 5 consisting of top panel member 6, bottom panel member 7, front and rear panel members 8 and 9 and end panel members 10 and 11. The front panel member 9 is apertured at 12 for the suspension of' the conical sound reproducing diaphragm 14 therein. An electromagnetic driver 15 is suspended from a depending support 16 mounted on the anel member 6. A link connection 17 is provided between the electromagnetic driver 15 and the sound reproducing diaphragm let. The panel member 7 is disposed at an angle with respect to the panel member 6 producing a gradual divergence of the walls of the housing 5 toward the front thereof for directing the sound outwardly through the grill work 4. The panel members 6 and 7 abut with the rear panel 8 against a sound proof gasket 18 forcing all of the sound from the rear of the sound reproducing diaphragm 14: to be directcd outwardly through the grill work at.

In order to detachably suspend the housing 5 within the main cabinet 1, I provide a pair of bracket members 19 and 20 which are secured to the top of cabinet 1. A cushion of felt or other sound proof material is carried as a lining or pad by the bracket members 19 and 20 which substantially prevents the transfer of microphonic disturbances from or to the electromagnetic sound reproducing apparatus. I have illustrated the pad as consisting of flat strips 21, 22, 23, 24, 25 and 26 which fit closely around the projecting ends of panel 6 forming a sound proof mounting therefor. In order to further insulate the electromagnetic sound reproducing apparatus I provide a front pad 27 against which panel 9 of the housing 5 abuts when the housing is moved to its final position within the main cabinet wall.

As illustrated in Fig. 5 the electromagnetic sound reproducing system may be readily removed from the main cabinet 1 or replaced therein by a horizontal movement within the main cabinet 1. This form of mounting facilitates the assembly of the apparatus and permits the inspection, repair and adjustment of the electromagnetic sound reproducing system to be readily made. The flexible conductors 28 lead from the electromagnetic driver 15 to the output circuit of the electron tube amplification system. Suficient freedom of movement is allowed to the conductors 28 for preventing the transfer of microphonic noises thereover which in cooperation with the sound proof mounting of the electromagnetic sound reproducer housing 5 practically eliminates noises arising from microphonic disturbances. Microphonic noises normally present in electromagnetic sound reproducing systems are very annoying and cause considerable interference with the reproduced signal energy. The local disturbances arising from mechanical vibration due to any natural movements, such. as walking upon the floor in the vicinity of the receiving apparatus often set up undesirable microphonic noises in the sound reproducing system. By my invention, however, these undesirable disturbances are substantially negligible.

What I claim and desire to secure by Letters Patent of the United States is as follows:

1. An electromagnetic sound reproducing system comprising in combination a housing, a sound reproducing diaphragm, an electromagnetic driver connected thereto and mounted within said housing, a main cabinet structure, a bracket member located adjacent opposite ends of said cabinet structure, sound proofing pads carried by each of said brackets for removably suspending said housing at opposite ends of said cabinet structure and means for preventing the transfer of microphonic noises to or from said electromagnetic sound reproducing system.

2. An electromagnetic sound reproducing system comprising a housing, an electromagnetic driver and sound reproducing diaphragm carried by said housing, a main cabinet structure, bracket members depending from 'said main cabinet structure for guiding said housing to a position within said main cabinet structure, and sound proof material interposed between said main cabinet structure and said housing and disposed along said bracket members for supporting said housing while eliminating the transfer of microphonic noises to or from said electromagnetic sound reproducing system.

3. An electromagnetic sound reproducing system comprising a substantially rectangular shaped easing, an electromagnetic driver suspended from the top of said casing, a sound reproducing diaphragm suspended from the front of said casing and actuated by said driver, the top of said casing extending beyond the opposite end walls of said casing, a main cabinet structure and sound proof material disposed about the opposite extremities of the top of said casing and bracket members depending from the top of the cabinet structure and arranged to engage the extremities of the top of said casing for suspending said casing from said main cabinet structure while eliminating the transfer of microphonic noises.

4t. An electromagnetic sound reproducing system comprising a main cabinet structure for housing electron tube amplification apparatus, electromagnetic sound reproducing apparatus for actuation by the amplification apparatus Within said cabinet structure, said electromagnetic sound reproducing apparatus being disposed within an in ependent housing, a pair of parallel extending rails secured to said main cabinet structure for supporting said housing, a pair of parallel extending rails secured to said main cabinet structure for supporting said housing, said independent housing being horizontally slidable from a position wholly within said main 1O cabinet structure to a position removed from said main cabinet structure, and means secured to the inner surfaces of said rails for preventing microphonic feedback between said independent housing and the amplification apparatus contained within main cabinet structure.

5. An electromagnetic sound reproducing system comprising a main cabinet structure for housing electron tube amplification apparatus, electromagnetic sound reproducing apparatus for actuation by the amplification apparatus within said cabinet structure, said electromagnetic sound reproducing apparatus being disposed within an independent housing, said independent housing being slidably mounted within said main cabinet structure in a substantially horizontal direction with sound proof material disposed between the side and top portions of said independent housing and all points of contact with said main cabinet structure for preventing the transfer of microphonic noises, a pair of bracket members depending from main cabinet structure for slidably receiving said housing and sound proof material secured to said bracket members for acoustically isolating said housing from said main cabinet structure for eliminating the transfer of microphonic noises.

6. An electromagnetic sound reproducing apparatus comprising a main cabinet structure for housing an electron tube amplification system, a pair of parallal extending guide members secured laterally below the top of said cabinet structure, an auxiliary cabinet structure arranged to be removably inserted within or withdrawn from said main cabinet structure in a substantially horizontal direction along said guide members, asound reproducing diaphragm carried by said auxiliary cabinet structure, an electromagnetic driver disposed within said auxiliary cabinet structure and connected withasaid sound reproducing diaphragm, and sound proofing material disposed between said main cabinet structure and the side and to walls of said auxiliary cabinet structure or preventing the transfer of microphonic noises therebetween. W In testimony whereof I aflix my signature.

WILLIAM BROWER. 

